N64oid is the very famous Nintendo 64 emulator optimized for Android. It is a port of Mupen64plus, along with Ari64's ARM dynarec (and gles2N64 as an option).

* Run most games smoothly at a reasonable speed (if not full speed) with sound. This requires you have a high-end device (Nexus-S, Galaxy-S, Xoom, etc).
* Good game compatibility compared to other N64 emulators running on mobile devices. And most likely more issues will be fixed in future updates.
* Save/load game states at ANY points, as well as in-game save support. Save files are fully compatible with Mupen64plus on PC.
* A configurable, translucent on-screen keypad that is very easy to use.
* Key mappings to map game keys to hardware buttons.
* Option to use the G-sensor as the analog stick.
* A variety of settings that you can tune on your needs.